My Onan was wo/rking perfectly when I shut it down. Started it up several days later and it was only charging 6 volts. By manually pushing the throttle to increase RPM it went up to 9 volts. I have had old Onans in boats with the same problem so I sent voltage regulator board out for inspection. Came back OK. Next I went to the large Onan dealer in town that charges $125/hour. Three hours later I was told that either the stator or rotor had shorted out. I was told the repair would be expensive and as the unit was old it wasn't worth fixing.
I am having a hard time believing that diagnosis. I can't get anyone to take a look at it--too old. But there must be other things that could cause the charging problem like those round capacitors?? (I know nothing about electronics) next to the board.
If anyone has a clue please share it. I really don't want--or have-- to spend the money to replace this genset.
Thanks
Oliver
1973 Kingsley
Patterson Engine
Alcoa Wheels

Oliver,

I've never had one fail, but your symptoms sound to me like the bridge
rectifier has failed.

Regardless, what you need to do is download and read:
http://gmcws.org/Tech/dsimmons/onan_demo/ . That will probably lead you
directly to the problem.

REMEMBER: Before you remove the bridge rectifier, MARK each of the 4
wires! Two of those 4 wires MUST connect to the correct (+ & -) terminals
on the bridge. The other 2 are interchangeable.

The KBPC5010 bridge rectifier readily available from eBay, etc., is a
suitable, economical, replacement, but you must modify the OEM connector
because of the different orientation of its terminals.

Ken H.


On Tue, Aug 18, 2020 at 1:35 PM Oliver Moore via Gmclist <
gmclist@list.gmcnet.org> wrote:

> My Onan was wo/rking perfectly when I shut it down. Started it up several
> days later and it was only charging 6 volts. By manually pushing the
> throttle to increase RPM it went up to 9 volts. I have had old Onans in
> boats with the same problem so I sent voltage regulator board out for
> inspection. Came back OK. Next I went to the large Onan dealer in town
> that charges $125/hour. Three hours later I was told that either the stator
> or rotor had shorted out. I was told the repair would be expensive and as
> the unit was old it wasn't worth fixing.
> I am having a hard time believing that diagnosis. I can't get anyone to
> take a look at it--too old. But there must be other things that could
> cause the charging problem like those round capacitors?? (I know nothing
> about electronics) next to the board.
> If anyone has a clue please share it. I really don't want--or have-- to
> spend the money to replace this genset.
> Thanks
> Oliver
> 1973 Kingsley
> Patterson Engine
> Alcoa Wheels
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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